Dielectric Properties of Fluid-Saturated Bone

The dielectric relaxation of bovine femoral compact bone specimens in vitro, saturated with 0.9 percent NaCI solution is determined by applying a constant current pulse and measuring the change in voltage with time. For specimens in which the current is in the plane perpendicular to the length of the whole bone and along the radial direction (radial specimens), the relaxation is confined to the time domain, t ≲50 μs; for longitudinal specimens, the relaxation, if any, would be for t ≲1 μs. The long-time resistivity of the latter is ≈45 to 48 Ωm; for the radial specimens, it is ≈3 to 4 times greater. The resistivity of the fluid is 0.72 Ωm. The results indicate that the dielectric behavior of fluid-saturated compact bone in vitro, and, hence, possibly also of in vivo bone, is determined mostly by the fluid-fllled pores. This has implications that contradict some of the commonly accepted views on the electromechanical effect in bone.